This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2001-129528, filed Apr. 26, 2001, the entire contents of which are incorporated herein by reference.
1. Field of the Invention
The present invention relates to an electrodeposition coating film thickness calculating method for calculating the thickness of an electrodeposition coating film, a recording medium stored with an electrodeposition coating film thickness calculating program and readable by means of a computer, and an electrodeposition coating film thickness simulation apparatus.
2. Description of the Related Art
Electrodeposition coating is carried out in a manner such that a to-be-coated object such as the body of an automobile, an anode, and a cathode are located in an electrolytic cell that is filled with an electrodeposition coating fluid, and a film is formed on the surface of the to-be-coated object by electrophoresis. In this electrodeposition coating, the film is first formed on the surface of an outside plate portion of the to-be-coated object that is subject to high voltage. The electrodeposition coating enjoys good throwing power such that paint particles gradually adhere to the inner part of the to-be-coated object that bears no film as the film resistance of the outside plate portion increases.
Owing to its high rustproof properties as well as the good throwing power, the electrodeposition coating is used as prime-coating for the underside of the body of an automobile.
Current easily flows through the outside of the to-be-coated object in a liquid and does not through the inside. A film cannot be easily formed inside a pouchy structure of the car body. It is hard, in particular, to form a film inside a frame member of the car body, such as a side frame portion that is expected to store a reinforcing material for safety, as well as the pouchy structure.
Thus, film formation requires thickness control.
In a conventional film control system, an actual production line is used to apply electrodeposition coating to an actually manufactured car body, in order to confirm satisfactory film formation. Thereafter, various parts of the car body are cut, and the thickness of a film on each inside part is measured to be checked for adequacy.
Using the actual car body, however, this thickness control is troublesome. If the throwing power of the film is insufficient, moreover, the film thickness measurement using the actual car body is expected to be repeated again after the throwing power is improved, so that substantial cost and time are required inevitably.
The object of the present invention is to provide an electrodeposition coating film thickness calculating method capable of calculating the respective thicknesses of films electrodeposited on various parts of a to-be-coated object with high accuracy by using data on an analytic model that replaces the to-be-coated object without using the actual to-be-coated object, a recording medium stored with an electrodeposition coating film thickness calculating program and readable by means of a computer, and an electrodeposition coating film thickness simulation apparatus.
In an aspect of the present invention, a thickness h of a film electrodeposited on the surface of the to-be-coated object is calculated according to h=xcexa3KFICC.E.xcex94t/xcfx81 (KF is an electrodeposit coating equivalent, IC is a film deposition current density, C.E. is a current efficiency, xcex94t is a time interval, and xcfx81 is a film density).
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.